[Tutor] IndexError: list index out of range : f2.write(col[0] + '\t' + col[1] + '\n')

[Max Noel]

On Nov 3, 2004, at 16:12, kumar s wrote:

> def cutter (f1,f2):
> 	file = open(f1,'r')
> 	file2 = open(f2,'w')
> 	fopen = file.read()
> 	flist = split(fopen,'\n')
> 	for i in range(len(flist)):
> 		col = split(flist[i],'\t')
> 		file2.write(col[0] + '\t' + col[1] + '\t' + col[3] +
> '\n' )
> 		file2.close()
>
>
>>>> cutter('gene_data.txt','test1.txt')
>
> Traceback (most recent call last):
>   File "<pyshell#44>", line 1, in -toplevel-
>     cutter('gene_data.txt','test1.txt')
>   File "<pyshell#42>", line 8, in cutter
>     file2.write(col[0] + '\t' + col[1] + '\t' + col[3]
> + '\n' )
> ValueError: I/O operation on closed file
>
>
> Why am I getting ValueError and I/O.  Why shouldnt I
> close file2.close()?

	That's because you're closing the file after each line. You should 
close it after the for loop instead.

	Also, you're using C-style for loops. A more elegant and 
memory-efficient (the way you're doing it, you load the whole file in 
memory, which is a Bad Thing if it's a big file) way to write your 
function using the file iterator:



def cutter(sourceName, destName):
     source = open(sourceName)	# Read-only is the default mode
     dest = open(destName, 'w')
     for line in source:
         col = split(line, '\t')
         dest.write('\t'.join(col) + '\n')
     dest.close()


	One last thing: you're naming your source file stream 'file', which is 
not a good idea given that file is a Python built-in class (for which 
open is an alias).

>
>
> 2nd Question:
>
>>>> cutter('gene_data.txt','test1.txt')
>
> Traceback (most recent call last):
>   File "<pyshell#47>", line 1, in -toplevel-
>     cutter('gene_data.txt','test1.txt')
>   File "<pyshell#46>", line 8, in cutter
>     file2.write(col[0] + '\t' + col[1] + '\t' + col[3]
> + '\n' )
> IndexError: list index out of range
>>>>
>
>
>
> Now, why am I getting IndexError: list out of range.
> What is the problem.  I got the result but an error is
> not so good. Can any one help me explaing the
> situation.

	That probably means that on the line for which you're getting the 
error, len(col) < 4.


-- Max
maxnoel_fr at yahoo dot fr -- ICQ #85274019
"Look at you hacker... A pathetic creature of meat and bone, panting 
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